As renewed interest in human space-exploration intensifies, a coherent and modernized strategy for mission design and planning has become increasingly crucial. Biotechnology has emerged as a promising approach to increase resilience, flexibility, and efficiency of missions, by virtue of its ability to effectively utilize in situ resources and reclaim resources from waste streams. Here we outline four primary mission-classes on Moon and Mars that drive a staged and accretive biomanufacturing strategy. Each class requires a unique approach to integrate biomanufacturing into the existing mission-architecture and so faces unique challenges in technology development. These challenges stem directly from the resources available in a given mission-class-the degree to which feedstocks are derived from cargo and in situ resources-and the degree to which loop-closure is necessary. As mission duration and distance from Earth increase, the benefits of specialized, sustainable biomanufacturing processes also increase. Consequentially, we define specific design-scenarios and quantify the usefulness of in-space biomanufacturing, to guide techno-economics of space-missions. Especially materials emerged as a potentially pivotal target for biomanufacturing with large impact on up-mass cost. Subsequently, we outline the processes needed for development, testing, and deployment of requisite technologies. As space-related technology development often does, these advancements are likely to have profound implications for the creation of a resilient circular bioeconomy on Earth.

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Graphene oxide (GO) has immense potential for widespread use in diverse in vitro and in vivo biomedical applications owing to its thermal and chemical resistance, excellent electrical properties and solubility, and high surface-to-volume ratio. However, development of GO-based biological nanocomposites and biosensors has been hampered by its poor intrinsic biocompatibility and difficult covalent biofunctionalization across its lattice. Many studies exploit the strategy of chemically modifying GO by noncovalent and reversible attachment of (bio)molecules or sole covalent biofunctionalization of residual moieties at the lattice edges, resulting in a low coating coverage and a largely bioincompatible composite. Here, we address these problems and present a facile yet powerful method for the covalent biofunctionalization of GO using colamine (CA) and the poly(ethylene glycol) cross-linker that results in a vast improvement in the biomolecular coating density and heterogeneity across the entire GO lattice. We further demonstrate that our biofunctionalized GO with CA as the cross-linker provides superior nonspecific biomolecule adhesion suppression with increased biomarker detection sensitivity in a DNA-biosensing assay compared to the (3-aminopropyl)triethoxysilane cross-linker. Our optimized biofunctionalization method will aid the development of GO-based in situ applications including biosensors, tissue nanocomposites, and drug carriers.

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In-situ resource utilization (ISRU) is increasingly acknowledged as an essential requirement for the construction of sustainable extra-terrestrial colonies. Even with decreasing launch costs, the ultimate goal of establishing colonies must be the usage of resources found at the destination of interest. Typical approaches towards ISRU are often constrained by the mass and energy requirements of transporting processing machineries, such as rovers and massive reactors, and the vast amount of consumables needed. Application of self-reproducing bacteria for the extraction of resources is a promising approach to reduce these pitfalls. In this work, the bacterium Shewanella oneidensis was used to reduce three different types of Lunar and Martian regolith simulants, allowing for the magnetic extraction of iron-rich materials. The combination of bacterial treatment and magnetic extraction resulted in a 5.8-times higher quantity of iron and 43.6% higher iron concentration compared to solely magnetic extraction. The materials were 3D printed into cylinders and the mechanical properties were tested, resulting in a 400% improvement in compressive strength in the bacterially treated samples. This work demonstrates a proof of concept for the on-demand production of construction and replacement parts in space exploration.

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The logistical supply of terrestrial materials to space is costly and puts limitations on exploration mission scenarios. In-situ resource utilization (ISRU) can alleviate logistical requirements and thus enables sustainable exploration of space. In this paper, a novel approach to ISRU, utilizing microorganisms to extract iron from Lunar or Martian regolith, is presented. Process yields, and kinetics are used to verify the theoretical feasibility of applying four different microorganisms. Based on yields alone, three of the four organisms were not investigated further for use in biological ISRU. For the remaining organism, Shewanella oneidensis, the survivability impact of Martian regolith simulant JSC-MARS1 and Mars-abundant magnesium perchlorate were studied and found to be minimal. The payback time of the infrastructure installation needed for the process with S. oneidensis on Mars was analyzed and the sensitivity to various parameters was investigated. Water recycling efficiency and initial regolith concentration were found to be key to process performance. With a water recycling efficiency of 99.99% and initial regolith concentration of 300 ​g/L, leading to an iron concentration of approximately 44.7 ​g/L, a payback time of 3.3 years was found.

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Transporting materials from Earth to Mars is a significant logistical constraint on mission design. Thus, a sustained settlement will be enhanced if it can perform elemental extraction and utilization in situ. In this study, all requirements to test a novel, biological approach for in situ resource utilization (ISRU) are conceptualized. We present designs for two bioreactor systems to be incorporated in a Mars habitat. The first system is a standard algae bioreactor which produces oxygen and biomass. The second bioreactor is capable of taking in Martian regolith and extracting enhanced iron ores from it via biological processes. Additionally, we propose the use of the leftover iron-poor but biomass rich material in a plant compartment. The multiple, different compartments feed into each other, creating an interconnected process enhancing self-sufficiency. In this paper, computational fluid dynamics of mixing behavior under reduced gravity, a breakdown of the process flow for a biological ISRU approach and exploratory in silico evaluation of the feasibility are presented.

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In situ resource utilization (ISRU) increasingly features as an element of human long-term exploration and settlement missions to the lunar surface. In this study, all requirements to test a novel, biological approach for ISRU are validated, and an end-to-end mission architecture is proposed. The general mission consists of a lander with a fully autonomous bioreactor able to process lunar regolith and extract elemental iron. The elemental iron could either be stored or directly utilized to generate iron wires or construction material. To maximize the success rate of this mission, potential landing sites for future missions are studied, and technical details (thermal radiation, shielding, power-supply) are analyzed. The final section will assess the potential mission architecture (orbit, rocket, lander, timeframe). This design might not only be one step further towards an international “Moon Village”, but may also enable similar missions to ultimately colonize Mars and further explore our solar system.@en

Bacteria and other microorganisms are known and studied as an essential part of daily life and they are utilized in a variety of fields. This work identifies applications in nanotechnology and space research, using the same bacterium for both: Shewanella oneidensis. The extracellular electron transfer (EET) mechanism situated mainly in the cell membrane of Shewanella oneidensis transports electrons, which are produced during its regular metabolic activity, to the outside of the cells. In the presence of certain metal oxides, the bacteria can reduce them while releasing carbon dioxide....@en

Graphene's maximized surface-to-volume ratio, high conductance, mechanical strength, and flexibility make it a promising nanomaterial. However, large-scale graphene production is typically cost-intensive. This manuscript describes a microbial reduction approach for producing graphene that utilizes the bacterium Shewanella oneidensis in combination with modern nanotechnology to enable a low-cost, large-scale production method. The bacterial reduction approach presented in this paper increases the conductance of single graphene oxide flakes as well as bulk graphene oxide sheets by 2.1 to 2.7 orders of magnitude respectively while simultaneously retaining a high surface-area-to-thickness ratio. Shewanella-mediated reduction was employed in conjunction with electron-beam lithography to reduce one surface of individual graphene oxide flakes. This methodology yielded conducting flakes with differing functionalization on the top and bottom faces. Therefore, microbial reduction of graphene oxide enables the development and up-scaling of new types of graphene-based materials and devices with a variety of applications including nano-composites, conductive inks, and biosensors, while avoiding usage of hazardous, environmentally-unfriendly chemicals.

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Biofilms are aggregates of bacteria embedded in a self-produced spatially-patterned extracellular matrix. Bacteria within a biofilm develop enhanced antibiotic resistance, which poses potential health dangers, but can also be beneficial for environmental applications such as purification of drinking water. The further development of anti-bacterial therapeutics and biofilm-inspired applications will require the development of reproducible, engineerable methods for biofilm creation. Recently, a novel method of biofilm preparation using a modified three-dimensional (3D) printer with a bacterial ink has been developed. This article describes the steps necessary to build this efficient, low-cost 3D bioprinter that offers multiple applications in bacterially-induced materials processing. The protocol begins with an adapted commercial 3D printer in which the extruder has been replaced with a bio-ink dispenser connected to a syringe pump system enabling a controllable, continuous flow of bio-ink. To develop a bio-ink suitable for biofilm printing, engineered Escherichia coli bacteria were suspended in a solution of alginate, so that they solidify in contact with a surface containing calcium. The inclusion of an inducer chemical within the printing substrate drives expression of biofilm proteins within the printed bio-ink. This method enables 3D printing of various spatial patterns composed of discrete layers of printed biofilms. Such spatially-controlled biofilms can serve as model systems and can find applications in multiple fields that have a wide-ranging impact on society, including antibiotic resistance prevention or drinking water purification, among others.

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Bioregenerative life support systems offer the advantage of simultaneously revitalizing air by fixing carbon dioxide and producing oxygen, purifying waste water, and generating human edible consumables by e.g. growing plants. The C.R.O.P.® (Combined Regenerative Organic food Production) biofilter system, developed at the Institute of Aerospace Medicine at the German Aerospace Center, is a sustainable concept for the improvement of wastewater in combination with plant cultivation. Two demonstrators incorporating C.R.O.P.® biofilters, a controlled growth environment, and a hydroponic growth method have been built at the European Space Agency under the Spaceship EAC initiative as an example for a bioregenerative life support system, as well as to investigate the operational concept around such a system. The design, execution and analysis of experiments in the demonstrators are presented. Experiments with Micro-Tina tomato plants (Lycopersicon esculentum Mill.) proved the functionality of the demonstrators. Environmental conditions such as temperature, humidity and photoperiod inside the growth chamber, as well as pH and electrical conductivity of the water were continuously observed and are found appropriate for plant growth. The addition of synthetic urine to the hydroponic system provides all nutrients required for tomatoes to grow through an entire lifecycle. The plants' total biomass, leaf area index and total number of tomatoes are significantly lower compared to the experiment with fertilizer as additive to the system. Another experiment where lunar regolith simulant is used as growth medium instead of rockwool germinated successfully, but plants are unable to develop flowers and fruits. In addition to the experiments, a simulation model of the C.R.O.P.® demonstrator is developed, partly based on experimental data for the conditions of the controlled environment. In order to predict crop performance, the simulation model implements the existing crop production models Modified Energy Cascade Model. Simulation results and experimental results are compared to validate the final C.R.O.P.® demonstrator model.@en

With current space exploration roadmaps indicating the Moon as a proving ground on the way to human exploration of Mars, it is clear that human-robotic partnerships will play a key role for successful future human space missions. This paper details a conceptual end-to-end architecture for an exploration mission in cis-lunar space with a focus on human-robot interactions, called Human Assisted Robotic Vehicle Studies (HARVeSt). HARVeSt will build on knowledge of plant growth in space gained from experiments on-board the ISS and test the first growth of plants on the Moon. A planned deep space habitat will be utilised as the base of operations for human-robotic elements of the mission. The mission will serve as a technology demonstrator not only for autonomous tele-operations in cis-lunar space but also for key enabling technologies for future human surface missions. The successful approach of the ISS will be built on in this mission with international cooperation. Mission assets such as a modular rover will allow for an extendable mission and to scout and prepare the area for the start of an international Moon Village.@en

Sustainable and personally tailored materials production is an emerging challenge to society. Living organisms can produce and pattern an extraordinarily wide range of different molecules in a sustainable way. These natural systems offer an abundant source of inspiration for the development of new environmentally friendly materials production techniques. In this paper, we describe the first steps toward the 3-dimensional printing of bacterial cultures for materials production and patterning. This methodology combines the capability of bacteria to form new materials with the reproducibility and tailored approach of 3D printing systems. For this purpose, a commercial 3D printer was modified for bacterial systems, and new alginate-based bioink chemistry was developed. Printing temperature, printhead speed, and bioink extrusion rate were all adapted and customized to maximize bacterial health and spatial resolution of printed structures. Our combination of 3D printing technology with biological systems enables a sustainable approach for the production of numerous new materials.

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